: Windy Santa Cruz of the University of Illinois at Urbana–Champaign and her colleagues have created a polymeric material that repairs itself when ruptured. The healing ability has two sources. First, the material is made porous by adding fibers in its hot, liquid state and removing them after it has cooled and solidified. Second, the channels created by the fibers are perfused with one of two liquids that form a gel when they combine and a plastic solid when left to react further. The healing springs into action when a rupture in the material causes the two different liquids to mingle. In one of their tests, Santa Cruz and her colleagues punched a 1-cm hole in the material. Within three hours, the hole had been completely filled with solid plastic.